A. Windows keeps track of devices and their configurations even when they're not present. Say you assign a static IP configuration to a NIC, remove that NIC, replace it with a new NIC, and then try to assign this new NIC the same IP address as the old one. You'll get a message that the IP address is already configured for a NIC that isn't present, and Windows will ask if you'd like to remove the configuration from the old NIC so you can use on your new one. You'll commonly get this message if you recreate virtual machine configurations and try to use the same IP address.
To see and remove an old NIC that's no longer present, you need to make device manager show devices that aren't present. Perform the following.
- Start an elevated cmd.exe session (as described here)
- Type the command
set devmgr_show_nonpresent_devices=1
devmgmt.msc - Device Manager will launch. Select "Show hidden devices" from the View menu.
- You'll now see disconnected devices as grayed out items that can be deleted, as shown in the figure (click to view in full size).
Notice in the above example that I have two Microsoft Virtual Machine Bus Network Adapters. The top one is grayed out because it's no longer connected, and it can be deleted.
